Merge branch 'rust-lang:master' into cstr-bytes-iter

.github/workflows/ci.yml

@@ -65,7 +65,7 @@ jobs:
     defaults:
       run:
         shell: ${{ contains(matrix.os, 'windows') && 'msys2 {0}' || 'bash' }}
-    timeout-minutes: 600
+    timeout-minutes: 240
     env:
       CI_JOB_NAME: ${{ matrix.image }}
       CARGO_REGISTRIES_CRATES_IO_PROTOCOL: sparse

.gitignore

@@ -50,6 +50,7 @@ build/
 /target
 /src/bootstrap/target
 /src/tools/x/target
+/inc-fat/
 # Created by default with `src/ci/docker/run.sh`
 /obj/
 /rustc-ice*

.ignore

@@ -0,0 +1,2 @@
+# Make vscode *not* count `config.toml` as ignored, so it is included in search
+!/config.toml

.reuse/dep5

@@ -36,6 +36,7 @@ Files: compiler/*
        .gitignore
        .gitmodules
        .mailmap
+       .ignore
 Copyright: The Rust Project Developers (see https://thanks.rust-lang.org)
 License: MIT or Apache-2.0
 

Cargo.lock

@@ -3141,7 +3141,19 @@ dependencies = [
  "bitflags 2.5.0",
  "getopts",
  "memchr",
- "pulldown-cmark-escape",
+ "pulldown-cmark-escape 0.10.1",
+ "unicase",
+]
+
+[[package]]
+name = "pulldown-cmark"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8746739f11d39ce5ad5c2520a9b75285310dbfe78c541ccf832d38615765aec0"
+dependencies = [
+ "bitflags 2.5.0",
+ "memchr",
+ "pulldown-cmark-escape 0.11.0",
  "unicase",
 ]
 
@@ -3151,6 +3163,12 @@ version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bd348ff538bc9caeda7ee8cad2d1d48236a1f443c1fa3913c6a02fe0043b1dd3"
 
+[[package]]
+name = "pulldown-cmark-escape"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "007d8adb5ddab6f8e3f491ac63566a7d5002cc7ed73901f72057943fa71ae1ae"
+
 [[package]]
 name = "pulldown-cmark-to-cmark"
 version = "13.0.0"
@@ -3401,6 +3419,8 @@ name = "run_make_support"
 version = "0.2.0"
 dependencies = [
  "ar",
+ "bstr",
+ "build_helper",
  "gimli 0.28.1",
  "object 0.34.0",
  "regex",
@@ -3460,6 +3480,13 @@ dependencies = [
  "stable_mir",
 ]
 
+[[package]]
+name = "rustc-perf-wrapper"
+version = "0.1.0"
+dependencies = [
+ "clap",
+]
+
 [[package]]
 name = "rustc-rayon"
 version = "0.5.0"
@@ -3488,6 +3515,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5be1bdc7edf596692617627bbfeaba522131b18e06ca4df2b6b689e3c5d5ce84"
 
+[[package]]
+name = "rustc-stable-hash"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5c9f15eec8235d7cb775ee6f81891db79b98fd54ba1ad8fae565b88ef1ae4e2"
+
 [[package]]
 name = "rustc-std-workspace-alloc"
 version = "1.99.0"
@@ -3826,6 +3859,7 @@ dependencies = [
  "portable-atomic",
  "rustc-hash",
  "rustc-rayon",
+ "rustc-stable-hash",
  "rustc_arena",
  "rustc_graphviz",
  "rustc_index",
@@ -4142,8 +4176,10 @@ dependencies = [
  "rustc_index",
  "rustc_macros",
  "rustc_middle",
+ "rustc_next_trait_solver",
  "rustc_span",
  "rustc_target",
+ "rustc_type_ir",
  "smallvec",
  "tracing",
 ]
@@ -4596,7 +4632,7 @@ name = "rustc_resolve"
 version = "0.0.0"
 dependencies = [
  "bitflags 2.5.0",
- "pulldown-cmark 0.9.6",
+ "pulldown-cmark 0.11.0",
  "rustc_arena",
  "rustc_ast",
  "rustc_ast_pretty",
@@ -4675,6 +4711,8 @@ name = "rustc_smir"
 version = "0.0.0"
 dependencies = [
  "rustc_abi",
+ "rustc_ast",
+ "rustc_ast_pretty",
  "rustc_data_structures",
  "rustc_hir",
  "rustc_middle",
@@ -4750,8 +4788,6 @@ checksum = "8ba09476327c4b70ccefb6180f046ef588c26a24cf5d269a9feba316eb4f029f"
 name = "rustc_trait_selection"
 version = "0.0.0"
 dependencies = [
- "bitflags 2.5.0",
- "derivative",
  "itertools",
  "rustc_ast",
  "rustc_ast_ir",
@@ -4760,7 +4796,6 @@ dependencies = [
  "rustc_errors",
  "rustc_fluent_macro",
  "rustc_hir",
- "rustc_index",
  "rustc_infer",
  "rustc_macros",
  "rustc_middle",
@@ -4773,7 +4808,6 @@ dependencies = [
  "rustc_target",
  "rustc_transmute",
  "rustc_type_ir",
- "rustc_type_ir_macros",
  "smallvec",
  "tracing",
 ]
@@ -4877,6 +4911,7 @@ dependencies = [
  "indexmap",
  "itertools",
  "minifier",
+ "pulldown-cmark 0.9.6",
  "regex",
  "rustdoc-json-types",
  "serde",
@@ -6331,9 +6366,9 @@ dependencies = [
 
 [[package]]
 name = "windows-bindgen"
-version = "0.57.0"
+version = "0.58.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ccb96113d6277ba543c0f77e1c5494af8094bf9daf9b85acdc3f1b620e7c7b4"
+checksum = "91cd28d93c692351f3a6e5615567c56756e330bee1c99c6bdd57bfc5ab15f589"
 dependencies = [
  "proc-macro2",
  "rayon",
@@ -6354,9 +6389,9 @@ dependencies = [
 
 [[package]]
 name = "windows-metadata"
-version = "0.57.0"
+version = "0.58.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8308d076825b9d9e5abc64f8113e96d02b2aeeba869b20fdd65c7e70cda13dfc"
+checksum = "2e837f3c3012cfe9e7086302a93f441a7999439be1ad4c530d55d2f6d2921809"
 
 [[package]]
 name = "windows-sys"

Cargo.toml

@@ -44,6 +44,7 @@ members = [
   "src/tools/rustdoc-gui-test",
   "src/tools/opt-dist",
   "src/tools/coverage-dump",
+  "src/tools/rustc-perf-wrapper",
 ]
 
 exclude = [

INSTALL.md

@@ -48,7 +48,7 @@ If building LLVM from source, you'll need additional tools:
   [LLVM's documentation](https://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library)
 * `ninja`, or GNU `make` 3.81 or later (Ninja is recommended, especially on
   Windows)
-* `cmake` 3.13.4 or later
+* `cmake` version listed on [LLVM's documentation](https://llvm.org/docs/GettingStarted.html#software)
 * `libstdc++-static` may be required on some Linux distributions such as Fedora
   and Ubuntu
 
@@ -215,7 +215,7 @@ python x.py build
 
 Right now, building Rust only works with some known versions of Visual Studio.
 If you have a more recent version installed and the build system doesn't
-understand, you may need to force rustbuild to use an older version.
+understand, you may need to force bootstrap to use an older version.
 This can be done by manually calling the appropriate vcvars file before running
 the bootstrap.
 

RELEASES.md

@@ -1,3 +1,161 @@
+Version 1.80 (2024-07-25)
+==========================
+
+<a id="1.80-Language"></a>
+
+Language
+--------
+- [Document maximum allocation size](https://github.com/rust-lang/rust/pull/116675/)
+- [Allow zero-byte offsets and ZST read/writes on arbitrary pointers](https://github.com/rust-lang/rust/pull/117329/)
+- [Support C23's variadics without a named parameter](https://github.com/rust-lang/rust/pull/124048/)
+- [Stabilize `exclusive_range_pattern` feature](https://github.com/rust-lang/rust/pull/124459/)
+- [Guarantee layout and ABI of `Result` in some scenarios](https://github.com/rust-lang/rust/pull/124870)
+
+<a id="1.80-Compiler"></a>
+
+Compiler
+--------
+- [Update cc crate to v1.0.97 allowing additional spectre mitigations on MSVC targets](https://github.com/rust-lang/rust/pull/124892/)
+- [Allow field reordering on types marked `repr(packed(1))`](https://github.com/rust-lang/rust/pull/125360/)
+- [Add a lint against never type fallback affecting unsafe code](https://github.com/rust-lang/rust/pull/123939/)
+- [Disallow cast with trailing braced macro in let-else](https://github.com/rust-lang/rust/pull/125049/)
+- [Expand `for_loops_over_fallibles` lint to lint on fallibles behind references.](https://github.com/rust-lang/rust/pull/125156/)
+- [self-contained linker: retry linking without `-fuse-ld=lld` on CCs that don't support it](https://github.com/rust-lang/rust/pull/125417/)
+- [Do not parse CVarArgs (`...`) as a type in trait bounds](https://github.com/rust-lang/rust/pull/125863/)
+- Improvements to LLDB formatting [#124458](https://github.com/rust-lang/rust/pull/124458) [#124500](https://github.com/rust-lang/rust/pull/124500)
+- [For the wasm32-wasip2 target default to PIC and do not use `-fuse-ld=lld`](https://github.com/rust-lang/rust/pull/124858/)
+- [Add x86_64-unknown-linux-none as a tier 3 target](https://github.com/rust-lang/rust/pull/125023/)
+- [Lint on `foo.into_iter()` resolving to `&Box<[T]>: IntoIterator`](https://github.com/rust-lang/rust/pull/124097/)
+
+<a id="1.80-Libraries"></a>
+
+Libraries
+---------
+- [Add `size_of` and `size_of_val` and `align_of` and `align_of_val` to the prelude](https://github.com/rust-lang/rust/pull/123168/)
+- [Abort a process when FD ownership is violated](https://github.com/rust-lang/rust/pull/124210/)
+- [io::Write::write_fmt: panic if the formatter fails when the stream does not fail](https://github.com/rust-lang/rust/pull/125012/)
+- [Panic if `PathBuf::set_extension` would add a path separator](https://github.com/rust-lang/rust/pull/125070/)
+- [Add assert_unsafe_precondition to unchecked_{add,sub,neg,mul,shl,shr} methods](https://github.com/rust-lang/rust/pull/121571/)
+- [Update `c_char` on AIX to use the correct type](https://github.com/rust-lang/rust/pull/122986/)
+- [`offset_of!` no longer returns a temporary](https://github.com/rust-lang/rust/pull/124484/)
+- [Handle sigma in `str.to_lowercase` correctly](https://github.com/rust-lang/rust/pull/124773/)
+- [Raise `DEFAULT_MIN_STACK_SIZE` to at least 64KiB](https://github.com/rust-lang/rust/pull/126059/)
+
+<a id="1.80-Stabilized-APIs"></a>
+
+Stabilized APIs
+---------------
+- [`impl Default for Rc<CStr>`](https://doc.rust-lang.org/beta/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3CCStr%3E)
+- [`impl Default for Rc<str>`](https://doc.rust-lang.org/beta/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3Cstr%3E)
+- [`impl Default for Rc<[T]>`](https://doc.rust-lang.org/beta/alloc/rc/struct.Rc.html#impl-Default-for-Rc%3C%5BT%5D%3E)
+- [`impl Default for Arc<str>`](https://doc.rust-lang.org/beta/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3Cstr%3E)
+- [`impl Default for Arc<CStr>`](https://doc.rust-lang.org/beta/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3CCStr%3E)
+- [`impl Default for Arc<[T]>`](https://doc.rust-lang.org/beta/alloc/sync/struct.Arc.html#impl-Default-for-Arc%3C%5BT%5D%3E)
+- [`impl IntoIterator for Box<[T]>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-IntoIterator-for-Box%3C%5BI%5D,+A%3E)
+- [`impl FromIterator<String> for Box<str>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-FromIterator%3CString%3E-for-Box%3Cstr%3E) 
+- [`impl FromIterator<char> for Box<str>`](https://doc.rust-lang.org/beta/alloc/boxed/struct.Box.html#impl-FromIterator%3Cchar%3E-for-Box%3Cstr%3E)
+- [`LazyCell`](https://doc.rust-lang.org/beta/core/cell/struct.LazyCell.html)
+- [`LazyLock`](https://doc.rust-lang.org/beta/std/sync/struct.LazyLock.html)
+- [`Duration::div_duration_f32`](https://doc.rust-lang.org/beta/std/time/struct.Duration.html#method.div_duration_f32)
+- [`Duration::div_duration_f64`](https://doc.rust-lang.org/beta/std/time/struct.Duration.html#method.div_duration_f64)
+- [`Option::take_if`](https://doc.rust-lang.org/beta/std/option/enum.Option.html#method.take_if)
+- [`Seek::seek_relative`](https://doc.rust-lang.org/beta/std/io/trait.Seek.html#method.seek_relative)
+- [`BinaryHeap::as_slice`](https://doc.rust-lang.org/beta/std/collections/struct.BinaryHeap.html#method.as_slice)
+- [`NonNull::offset`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.offset)
+- [`NonNull::byte_offset`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.byte_offset)
+- [`NonNull::add`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.add)
+- [`NonNull::byte_add`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.byte_add)
+- [`NonNull::sub`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.sub)
+- [`NonNull::byte_sub`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.byte_sub)
+- [`NonNull:offset_from`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.offset_from)
+- [`NonNull::byte_offset_from`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.byte_offset_from)
+- [`NonNull::read`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.read)
+- [`NonNull::read_volatile`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.read_volatile)
+- [`NonNull::read_unaligned`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.read_unaligned)
+- [`NonNull::write`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.write)
+- [`NonNull::write_volatile`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.write_volatile)
+- [`NonNull::write_unaligned`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.write_unaligned)
+- [`NonNull::write_bytes`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.write_bytes)
+- [`NonNull::copy_to`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.copy_to)
+- [`NonNull::copy_to_nonoverlapping`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.copy_to_nonoverlapping)
+- [`NonNull::copy_from`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.copy_from)
+- [`NonNull::copy_from_nonoverlapping`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.copy_from_nonoverlapping)
+- [`NonNull::replace`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.replace)
+- [`NonNull::swap`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.swap)
+- [`NonNull::drop_in_place`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.drop_in_place)
+- [`NonNull::align_offset`](https://doc.rust-lang.org/beta/std/ptr/struct.NonNull.html#method.align_offset)
+- [`<[T]>::split_at_checked`](https://doc.rust-lang.org/beta/std/primitive.slice.html#method.split_at_checked)
+- [`<[T]>::split_at_mut_checked`](https://doc.rust-lang.org/beta/std/primitive.slice.html#method.split_at_mut_checked)
+- [`str::split_at_checked`](https://doc.rust-lang.org/beta/std/primitive.str.html#method.split_at_checked)
+- [`str::split_at_mut_checked`](https://doc.rust-lang.org/beta/std/primitive.str.html#method.split_at_mut_checked)
+- [`str::trim_ascii`](https://doc.rust-lang.org/beta/std/primitive.str.html#method.trim_ascii)
+- [`str::trim_ascii_start`](https://doc.rust-lang.org/beta/std/primitive.str.html#method.trim_ascii_start)
+- [`str::trim_ascii_end`](https://doc.rust-lang.org/beta/std/primitive.str.html#method.trim_ascii_end)
+- [`<[AsciiChar]>::trim_ascii`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.trim_ascii)
+- [`<[AsciiChar]>::trim_ascii_start`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.trim_ascii_start)
+- [`<[AsciiChar]>::trim_ascii_end`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.trim_ascii_end)
+- [`Ipv4Addr::BITS`](https://doc.rust-lang.org/beta/core/net/struct.Ipv4Addr.html#associatedconstant.BITS)
+- [`Ipv4Addr::to_bits`](https://doc.rust-lang.org/beta/core/net/struct.Ipv4Addr.html#method.to_bits)
+- [`Ipv4Addr::from_bits`](https://doc.rust-lang.org/beta/core/net/struct.Ipv4Addr.html#method.from_bits)
+- [`Ipv6Addr::BITS`](https://doc.rust-lang.org/beta/core/net/struct.Ipv6Addr.html#associatedconstant.BITS)
+- [`Ipv6Addr::to_bits`](https://doc.rust-lang.org/beta/core/net/struct.Ipv6Addr.html#method.to_bits)
+- [`Ipv6Addr::from_bits`](https://doc.rust-lang.org/beta/core/net/struct.Ipv6Addr.html#method.from_bits)
+- [`Vec::<[T; N]>::into_flattened`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html#method.into_flattened)
+- [`<[[T; N]]>::as_flattened`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.as_flattened)
+- [`<[[T; N]]>::as_flattened_mut`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.as_flattened_mut)
+
+These APIs are now stable in const contexts:
+
+- [`<[T]>::last_chunk`](https://doc.rust-lang.org/beta/core/primitive.slice.html#method.last_chunk)
+- [`BinaryHeap::new`](https://doc.rust-lang.org/beta/std/collections/struct.BinaryHeap.html#method.new)
+
+<a id="1.80-Cargo"></a>
+
+Cargo
+-----
+- [Stabilize `-Zcheck-cfg` as always enabled](https://github.com/rust-lang/cargo/pull/13571/)
+- [Warn, rather than fail publish, if a target is excluded](https://github.com/rust-lang/cargo/pull/13713/)
+- [Add special `check-cfg` lint config for the `unexpected_cfgs` lint](https://github.com/rust-lang/cargo/pull/13913/)
+- [Stabilize `cargo update --precise <yanked>`](https://github.com/rust-lang/cargo/pull/13974/)
+- [Don't change file permissions on `Cargo.toml` when using `cargo add`](https://github.com/rust-lang/cargo/pull/13898/)
+- [Support using `cargo fix` on IPv6-only networks](https://github.com/rust-lang/cargo/pull/13907/)
+
+<a id="1.80-Rustdoc"></a>
+
+Rustdoc
+-----
+
+- [Allow searching for references](https://github.com/rust-lang/rust/pull/124148/)
+- [Stabilize `custom_code_classes_in_docs` feature](https://github.com/rust-lang/rust/pull/124577/)
+- [fix: In cross-crate scenarios show enum variants on type aliases of enums](https://github.com/rust-lang/rust/pull/125300/)
+
+<a id="1.80-Compatibility-Notes"></a>
+
+Compatibility Notes
+-------------------
+- [rustfmt estimates line lengths differently when using non-ascii characters](https://github.com/rust-lang/rustfmt/issues/6203)
+- [Type aliases are now handled correctly in orphan check](https://github.com/rust-lang/rust/pull/117164/)
+- [Allow instructing rustdoc to read from stdin via `-`](https://github.com/rust-lang/rust/pull/124611/)
+- [`std::env::{set_var, remove_var}` can no longer be converted to safe function pointers and no longer implement the `Fn` family of traits](https://github.com/rust-lang/rust/pull/124636)
+- [Warn (or error) when `Self` constructor from outer item is referenced in inner nested item](https://github.com/rust-lang/rust/pull/124187/)
+- [Turn `indirect_structural_match` and `pointer_structural_match` lints into hard errors](https://github.com/rust-lang/rust/pull/124661/)
+- [Make `where_clause_object_safety` lint a regular object safety violation](https://github.com/rust-lang/rust/pull/125380/)
+- [Turn `proc_macro_back_compat` lint into a hard error.](https://github.com/rust-lang/rust/pull/125596/)
+- [Detect unused structs even when implementing private traits](https://github.com/rust-lang/rust/pull/122382/)
+- [`std::sync::ReentrantLockGuard<T>` is no longer `Sync` if `T: !Sync`](https://github.com/rust-lang/rust/pull/125527) which means [`std::io::StdoutLock` and `std::io::StderrLock` are no longer Sync](https://github.com/rust-lang/rust/issues/127340)
+
+<a id="1.80-Internal-Changes"></a>
+
+Internal Changes
+----------------
+
+These changes do not affect any public interfaces of Rust, but they represent
+significant improvements to the performance or internals of rustc and related
+tools.
+
+- Misc improvements to size of generated html by rustdoc e.g. [#124738](https://github.com/rust-lang/rust/pull/124738/) and [#123734](https://github.com/rust-lang/rust/pull/123734/)
+- [MSVC targets no longer depend on libc](https://github.com/rust-lang/rust/pull/124050/)
+
 Version 1.79.0 (2024-06-13)
 ==========================
 

compiler/rustc_abi/src/layout.rs

@@ -186,7 +186,7 @@ pub trait LayoutCalculator {
         let (present_first, present_second) = {
             let mut present_variants = variants
                 .iter_enumerated()
-                .filter_map(|(i, v)| if absent(v) { None } else { Some(i) });
+                .filter_map(|(i, v)| if !repr.c() && absent(v) { None } else { Some(i) });
             (present_variants.next(), present_variants.next())
         };
         let present_first = match present_first {
@@ -621,7 +621,7 @@ where
     let discr_type = repr.discr_type();
     let bits = Integer::from_attr(dl, discr_type).size().bits();
     for (i, mut val) in discriminants {
-        if variants[i].iter().any(|f| f.abi.is_uninhabited()) {
+        if !repr.c() && variants[i].iter().any(|f| f.abi.is_uninhabited()) {
             continue;
         }
         if discr_type.is_signed() {